As numbers of computers, particularly servers, are deployed in large-scale or hyper-scale data center applications, the need to connect those computers to one another at massive scale as well as to connect them to the outside world has driven change in data center networking topologies and strategies.
Two of the primary drivers of cost and performance in these large networks are the network topology and the photonic interconnections between them. The trend has been to utilize many low-cost low-radix switches that are connected to other low-radix switches via many connections, both copper and optical. As the networks increase efficiency by increasing data rate, the distances that can be traversed by copper cables are diminished. As a result, the ratio of copper cables to optical cables has trended increasingly in favor of optical cables.